Aseptic slicing machine for food products, and method

ABSTRACT

To prevent accelerated spoilage of sliced food products, particularly meat, cold cuts and the like, the knife of a slicing machine is heated so that it will have continuously, a temperature which it is high enough to be sterilizing temperature, over 100*C, and preferably in the order of about 120*C. The knife is preferably heated by blowing air at a temperature between 200*C and 350*C against the knife blade. The solid, or block food products are protected by a hood, into which sterilized cool air is introduced, for example, in the order of ambient temperature, such as between 18*C and 28*C, and a sterile atmosphere is additional preferably enhanced by operating an ultra violet lamp within the hood. The sliced food products are transported away from the cutting blade by a protected transport path, and protected by a hood, and, preferably cooled, in an atmosphere of sterilized air, at a slight overpressure, and preferably also in the presence of UV radiation so that they can be packaged under sterilized conditions and contamination of the sliced top faces of food products, prior to packaging, is inhibited.

United States Patent Laderach 1 Dec. 23, 1975 ASEPTIC SLICING MACHINEFOR FOOD PRODUCTS, AND METHOD [57] ABSTRACT [75] Inventor; H R Laderach,Basemheid To prevent accelerated spoilage of sliced food prodswitzerlanducts, particularly meat, cold cuts and the like, the

i knife of a slicing machine is heated so that it will have [73]Asslgnee: M'cama AG nelschwarenfabnk, continuously, a temperature whichit is high enough to Bazenheld, Swltzerland be sterilizing temperature,over 100C, and preferably [22] Fil d; J 22, 1974 in the order of about120C. The knife is preferably heated b blowin air at a tem eraturebetween 200C [21] APPI' 490,518 and 350 c agains t the knife bl de. Thesolid, or block food products are protected by a hood, into which 52 US.Cl. 83/15; 83/170; 83/171; sterilized cool air is introduced, forexample, in the 99 517; 42 5 426/524 order of ambient temperature, suchas between 18C 51 im. C1 A23B 4/06; B26D 4/22 and 28C, and a Sterileatmosphere is additional P [58] Field of Search 83/15, 16, 170, 171;erably enhanced by Operating an ultra violet p 99 517; 426/518 5 withinthe hood. The sliced food products are transported away from the cuttingblade by a protected [56] References Cited transport path, and protectedby a hood, and, prefera- UNITED STATES PATENTS bly cooled, in anatmosphere of sterilized air, at a slight overpressure, and preferablyalso in the pres- B 83/ ence of UV radiation so that they canbe-packaged 338551912 12/1974 831 1322221361; 51111111115551? x understerilized conditions and contamination of the Primary ExaminerWillie G.Abercrombie Attorney, Agent, or FirmFlynn & Frishauf sterile air slicedtop faces of food products, prior to packaging, is inhibited.

11 Claims, 3 Drawing Figures 8 Cool sterile US. Patent Dec. 23, 1975Sheet 1 of 3 3,927,588

4 252 8 5391 szerile/7 sterile :11!"

Fig. i

U.S. Patent Dec. 23, 1975 Sheet 2 of 3 3,927,588

US. Patent Dec. 23, 1975 Sheet 3 of3 3,927,588

Hot sterile air PREHEATER COOLER Fig. 3

Compressed ASEPTIC SLICING MACHINE FOR FOOD PRODUCTS, AND METHOD Thepresent invention relates to a method to aseptically sever food productsand .particularlymeat and sausage products to prepare'cold cuts, andlike, by means of a slicing machine. i

It is well known that the storage capability of meat products, sausagesand the like'which is cut in slices is less than'similar products inblock,-or bulk form.' It is of substantial importance in super marketand self-service establishments tobe able to sell sliced meat productsin packaged form. Spoilage is, however, a continuousproblem and it is ofimportance that the storage time of sliced meat, meat products,sausages, and the like,'can be extended. Numerous attempts have beenmade to increasethe storage time, and retard spoilage of sliced meatproducts, for example by means of vacuum packirig'fUnfortunately, it hasbeen found that meat products which have a tendency to spoil-can not bestored, satisfactorily, for extended periods, even when vacuum packedand kept at low temperatures, for example, in refrigerators, inrefrigerated display cases.

It is the object of the present invention to increase the storage timecapability of sliced cut meat and sausage products, so that they can bepackaged,'as sliced products for sale as packaged units in self-serviceestablishments.

SUBJECT MATTER OF THE PRESENT INVENTION Briefly, the 'slicing knife ofthe cutting machine, se-

quentially severing slices of food product from a bulk supply iscontinually maintained at the temperature which is at least the minimumsterilizing temperature. In accordance with a preferred form of theinvention, the region of the slicing machine or which the knife orcutting blade operates, and preferably, also the feed roll for the bulkmeat products supplyand the transport path carrying thesevered slicesaway, are shrouded by one or more hoods, into which sterilized air isintroduced. Heated air, for example in a temperature range of between200C and 350C is blown against the cutting knife, to keep the cuttingknife at a temperature above 100C. A temperature range from between [Cand l30C,is suitable and a temperature in the order of about IC ispreferred. Sterility of the surrounding of the cutting operation can beadditionally enhanced, in accordance with the feature of the invention,by introducing a source of ultra violet radiation in thehood shieldingthe bulk and the severed meat product.

It is believed that the undesirable storage capability of sliced or cutmeat products appears to be primarily dueto the introduction of germs,and the like, during the cutting operation and particularly by thecutting knife. The cutting knife, customarily of the rotary type,touches-the entire cut surface of each severed slice. Any germs andbacteria, other contaminants in ambi- -ent air and on the outer surfaceof bulk meat products are distributed by the cutting knifeover thesurface of the freshly cut slice. By heating the cuttingknife tosterilization temperature, germs, bacteria and other contaminants arenot transferred to the cut out surface of the freshly cut" slices," thus'substantially' increasing the storage time of theslice'd products.

. The invention will be described by way of example O slicing machine;and FIG. 3 is a schematic side view of l the sterile airgenerating-system, with parts of the housings drawn broken away andillustrating the interior, in

section.

.The slicing machine itself may be, any type of commerciallyav-ailableand well known meat slicing machine. Basically, a frame orhousing (FIG. 1) supports an inclined slide 2 on which thebulk foodproduct 19 (FIG. 2) issretained. The slide 2 is secured by a pair ofcylindricalrods 24. The bulk food product 19, shown only schematically,issecured on the slide by a feed transport chain system 20, having upperand lower horizontal connected bars, 30-31. Slide 2 is covered by a hood8 which can tilt about hinge 33. I Slicing is doneby a rotary cuttingblade 4, driven by a motor,,which rotates about its own axis. The axisof rotation of blade 4 is further secured to a rotating excenter so thatthe cutting blade 4 carries out a to-and-fro reciprocating, swingingmotion, in which the cutting blade 4 is carried in front of the bulkfood product 19 to cut off a slice, and then is retracted away fromthebulk product 19 so that the bulk product canbe fed by the thickness ofthe slice, for subsequent severing by the cutting knife, which againpasses over the bulk product 19. The bulk product 19 is fed by a feedspindle 25 driven .by a motor 5. Slicing machines are well known.

The cutting blade 4 is protected from ambient air surrounded by aprotected housing 6; a hot air duct 7 terminates in housing 6. The hotair duct 7, preferably, is a flexible heat-resistant hose. The hot airduct 7 terminates in a nozzle 23 which directs sterile heated air comingfrom the hot air duct 7, against the cutting blades 4. Cutting blade 4is heated continuously to a temperature which is at least sterilizationtemperature. The temperature of the hot air itself is higher than thecutting knife 4 which is continuously cooled bycontact with the bulkfood product during the cutting opera- ;tion. The temperature at whichthe cutting blade or knife 4 is continuously maintained is preferably inthe order of about 121C, and should be in the range of between C andl,30 C. Hot air blown against the cutting knife or blade 4 preferably isin a temperature range of about 200C to 350C.

Nozzle 23 may include a pipe stub, locatedparallel to the cutting planeof the knife 4, which is formed with a plurality of openings directedagainst the cutting blade 4. The region .or zone in the vicinity of thecutting blade 4 is thus subjected to a slight over-pressure due to theintroduced hot air, which prevents penetration of nonsterile ambientair, and protectively surrounds the cutting blade. The hot air mayescape through openings, not further shown, or leak and other cracks inthe protective hood housing 6. H

In accordance with, a feature of the invention, the air within hood.;8is also sterile. A sterile air supply hose 21 is collected through asterile air duct 10 leading into the hood 8. Sterile airblown into theinside .of hood 8 through distribution nozzle 11. Direct air blast '34is so directed that a curtain of sterile air is formed around the bulkfood product. The temperature of the introduced sterile air may be atambiant temperature, and preferably in the range of about l8C to 28C.Over pressure of sterile air will result beneath the hood 8, so thatnon-sterile ambient air from the outside of the cutting machine can notreach the bulk food product. An ultra violet lamp 12 is located withinthe hood 8. Such lamps have bacteriostatic effect.

The sliced meat product, cut by the blade 4 drops on a continuouslymovable transport belt 14. Transport belt 14 is part of a transportsystem, located on a table 15. The transport system is covered by a hood16 which, in cross section, is generally U-shaped. The transport belt 14is endless; UV radiation is directed by lamp 12' on the lower side ofthe endless transport belt 14 during its return run, so that the beltitself is sterilized. The cut slices on the transport belt aretransported to a packaging machine, for example, through an automaticpackaging machine through which they are packaged under sterileconditions.

The sterile air is generated, as best seen in FIG. 3, by a sterile airgenerating system which includes a preheater 40, a main heater l8, and acooling unit 53. The three separate units are secure to housing 1, onebehind the other, so that only one thereof is visible in FIG. 1. Airsupplied over duct 41, for example open to ambient air, is preheated inthe cylindrical preheater 40; thereafter, it is conducted to a mainheater 18 which is combined with a air heater 49, to bring the air tothe desired temperature of between 200 and 350C. By heating andfiltering, sterile hot air is obtained. A portion of this hot air isconducted by hose 7 to be directed to knife 4. Another portion of thissterilized hot air is conducted by duct 52, which includes a valve, to acooling unit 53, in which the sterile air is cooled to approximatelyroom temperature, for example to between l8C to 28C. This cooledsterilized air is then supplied by means of hose 21, or by means of anyother suitable means of conduit or tube to hose 21 and similar hoses-(not shown) him the interior of the hood 16 surrounding the transportbelt 14. Suitable control valves are provided to control the portions orfractions of the cooled sterilized air supplied through the valves tothe enclosed hooded chambers.

Ambient air, at a pressure higher than ambient pressure, that is,pressure about from 3 to bars are introduced over duct 41 into theinterior of the cylindrical vessel 44, forming the preheater. Coiledelectrical heaters 42, 43, are located within the vessel 44 to heat theintroduced air. The upper end of the preheater vessel 44 includes anoutlet stub 45 which is connected over a connecting flange 46 to aninlet stub integral with the heating vessel 47 of the main heating unit18. A spiraled electrical heating element 48 is located within thecylindrical vessel 47, surrounding a tubular air filter 49, with radialspacing. Air filter 49 may be, for example, to sintered metal filter Afurther spiral heat element 51 is located within the porous air filter49. The hot air which has penetrated through filter 49 is collected inthe cylindrical vertical space 50, heated by filter 51, to be removed byhose 7 and by duct 52. That portion of the hot air which passes in duct52 is cooled in cooling unit 53 to approximately room temperature.Cooling unit 53 may be for example, water cooler through which water iscirculated. A cooling coil 55 is located within the vessel 54 formingthe cooler. 53. Cooling water is circulated through the cooling coil 55,supplied by a line 56 and removed from an outlet duct 57. The

sterilized air, now cooled, is removed from cooler 53 by duct 21 locatedat the upper end thereof. The cooler may equally well be constructed inthe reverse, that is conduct the air from duct 52 through a coil,surrounded by cooling water flowing through the vessel.

The entire zones or regions in the vicinity of the cutting operation isthus sterilized; cutting is accomplished aseptically, withoutcomplicating the cutting process, as such.

The cutting blade or knife 4 preferably is sterilized by heated air, asdescribed; it may, however, be brought to sterilization temperature alsoby other means, for example by electrical resistance heating, inductionheating, or flame heating, for example by means of a gas flame. l-lotair is, however, preferred since, if the cutting knife should stop in aposition exposed to the heating unit, localized hot spots which mightdamage the cutting knife are thereby avoided. The arrangement, thus,does not require expensive interlock apparatus to reduce localizedheating; such localized heating cannot be interrupted, merely, uponinterruption of the cutting operation since otherwise sterility of theentire process is vitiated.

Various changes and modifications may be made within the scope of theinventive concept.

The cooling and heating of air can be combined by operating the coolingunit in a compression-expansion refrigeration cycle; the condenser, tocool the refrigerant, can itself be cooled by air being introduced frompipe 41, and act either as a pre-cooling unit 40 or, at least in part,also as the main heater 18; the cooling system of the refrigerationcycle, after expansion of the refrigerant gas then can be located incooler 53. Some additional heating energy may be necessary to bring theair to the temperature required to sterilize the knife 4. The airsupplied over pipe 41, at overpressure, may already be pre-filtered. Ifthe heating-cooling system includes refrigeration-cycle equipment, thenthe spiral resistance heater elements 43, 48, 51 may be replaced byspiralel tubings similar to tubing 55 which, additionally, preferably isfinned to increase the heat exchange surface.

I claim:

1. Method of aseptically severing meat products, sausage products, coldcuts, and the like, utilizing a slicing machine having a moving cuttingknife sequentially severing slices of said meat products from a bulk ppy comprising the step of continually blowing air at a temperature inexcess of C against said cutting knife to continuously maintain thecutting knife (4) of the slicing machine during the cutting operation ata temperature which is at least the minimum sterilization temperatureand to heat the cutting knife to a temperature in excess of 100C.

2. Method according to claim 1, wherein said blowing step comprises thestep of blowing the air at the temperature in excess of 100C against thecutting knife in a region remote from the end face of the bulk foodproduct (19).

3. Method according to claim 1 wherein said airblo'wing step comprisesconstantly blowing sterilized air towards the cutting knife.

4. Slicing machine for aseptically severing meat products, sausageproducts, cold cuts and the like into slices comprising means (20, 30,31)

supporting said food product (U) in unsliced, bulk form;

a cutting knife (40) movable back-and-forth across the bulk food productto sever slices therefrom comprising the improvement of means (18)heating air to sterilizing temperature and at least to 100C;

at least one heated air outlet (23) connected to the air heating means(18) and located in the vicinity of the cutting knife (4) andcontinuously blowing heated air toward the cutting knife in a regionremote from the end face of the bulk food product (19) to continuouslyheat the cutting knife to a temperature which is at least sterilizingtempera-' ture.

5. Machine according to claim 4 further comprising a hood (8)surrounding the food product (19); and

means (21) supplying cold, sterilized air beneath the hood to surroundthe food product and provide a region of over pressure of sterilized airbeneath said hood.

6. Machine according to claim 5 further comprising a source of ultraviolet radiation (12) located beneath the hood and irradiating the spacethere beneath, in which the food product are located.

7. Machine according to claim 5 wherein the air heating means comprisesan air heater (l8) heating air through and to sterilizing temperature;

a cooling unit (53) is provided, connected to receive at least a portionof said heated sterilized aiar and cooling said heated sterilized air;

and connecting means to connect said cool, heatsterilized air to a duct(10) and to the hood (8).

8. Machine according to claim 7 wherein the hood is (8) located tosurround the bulk food product (19) being fed to the knife (4).

9. Machine according to claim 4 further comprising a removal transportmeans (14) located to remove sliced food products;

wherein the improvement comprises a hood (16) covering said transportmeans and said slices thereon;

and means sterilizing the air surrounding said sliced food products.

10. Machine according to claim 9 wherein the means sterilizing the airsurrounding the sliced food product comprise duct means (21) supplyingsterilized air to a sliced food product. 7

11. Machine according to claim 4 further comprising endless transportmeans having a removal path and a return path therebeneath and locatedto remove sliced food product, wherein the improvement comprises meanssterilizing the transport means while in the return path including asource of ultra violet radiation (12') located to irradiate thetransport means while in the return path.

1. Method of aseptically severing meat products, sausage products, cold cuts, and the like, utilizing a slicing machine having a moving cutting knife sequentially severing slices of said meat products from a bulk supply comprising the step of continually blowing air at a temperature in excess of 100* C against said cutting knife to continuously maintain the cutting knife (4) of the slicing machine during the cutting operation at a temperature which is at least the minimum sterilization temperature and to heat the cutting knife to a temperature in excess of 100*C.
 2. Method according to claim 1, wherein said blowing step comprises the step of blowing the air at the temperature in excess of 100*C against the cutting knife in a region remote from the end face of the bulk food product (19).
 3. Method according to claim 1 wherein said airblowing step comprises constantly blowing sterilized air towards the cutting knife.
 4. Slicing machine for aseptically severing meat products, sausage products, cold cuts and the like into slices comprising means (20, 30, 31) supporting said food product (19) in unsliced, bulk form; a cutting knife (40) movable back-and-forth across the bulk food product to sever slices therefrom comprising the improvement of means (18) heating air to sterilizing temperature and at least to 100*C; at least one heated air outLet (23) connected to the air heating means (18) and located in the vicinity of the cutting knife (4) and continuously blowing heated air toward the cutting knife in a region remote from the end face of the bulk food product (19) to continuously heat the cutting knife to a temperature which is at least sterilizing temperature.
 5. Machine according to claim 4 further comprising a hood (8) surrounding the food product (19); and means (21) supplying cold, sterilized air beneath the hood to surround the food product and provide a region of over pressure of sterilized air beneath said hood.
 6. Machine according to claim 5 further comprising a source of ultra violet radiation (12) located beneath the hood and irradiating the space there beneath, in which the food product are located.
 7. Machine according to claim 5 wherein the air heating means comprises an air heater (18) heating air through and to sterilizing temperature; a cooling unit (53) is provided, connected to receive at least a portion of said heated sterilized aiar and cooling said heated sterilized air; and connecting means to connect said cool, heat-sterilized air to a duct (10) and to the hood (8).
 8. Machine according to claim 7 wherein the hood is (8) located to surround the bulk food product (19) being fed to the knife (4).
 9. Machine according to claim 4 further comprising a removal transport means (14) located to remove sliced food products; wherein the improvement comprises a hood (16) covering said transport means and said slices thereon; and means sterilizing the air surrounding said sliced food products.
 10. Machine according to claim 9 wherein the means sterilizing the air surrounding the sliced food product comprise duct means (21) supplying sterilized air to a sliced food product.
 11. Machine according to claim 4 further comprising endless transport means having a removal path and a return path therebeneath and located to remove sliced food product, wherein the improvement comprises means sterilizing the transport means while in the return path including a source of ultra violet radiation (12'') located to irradiate the transport means while in the return path. 